E109 Midterm 2

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  1. how the heart pumps
    • heart contraction reduces chamber volume
    • reducing volume elevates pressure
    • fluid moves toward lower pressure
    • valves prevent backflow
    • downstream low pressure opens a valve
    • upstream low pressure closes a valve
    • two valves facilitate unidirectional flow
  2. vein
    a vessel that delivers blood toward the heart
  3. artery
    a vessel that transports blood away from the heart
  4. atrial systole
    ventricles expand with blood from atria
  5. early ventricular systole
    AV valves close and there is no blood flow
  6. late ventricular systole
    semilunar valves open and blood flows from ventricles
  7. atrial diastole
    atria fill with blood from venae cavae and pulmonary veins
  8. early ventricular diastole
    semilunar valves close
  9. late ventricular diastole
    AV valves open and ventricles fill with blood
  10. cardiac cycle - sequence of valves opening and closing
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  11. Poiseuille's Law
    • viscosity causes radius to affect resistance, and causes a loss of pressure
    • only applies to smaller vessels of the capillaries and arterioles (not the aorta), and to fluids due to their viscosity
    • formally, this is a physical law that gives the pressure drop in a fluid flowing through a long cylindrical pipe
  12. measure of blood pressure and velocity during circulation
  13. mean arterial pressure (MAP)
    • MAP = Pdiastolic + 1/3 (Psystolic -Pdisastolic)
    • MAP equation gives a weighted average that is closer to the diastolic pressure because the heart is in diastole longer than in systole
    • MAP = cardiac output x resistance of the arterioles with resistance proportional to 1/r^4
  14. change in pressure - formula
    • change in pressure = Q x R 
    • Q is flow rate and R is resistance
  15. elevated pressure in arteries
    • the connective tissue lining the walls of the arterioles contain elastic tissue made of collagen fibers that are elastic, causing pressure to remain high
    • during systole, expansion of elastic walls expand and remain in tension throughout diastole, never reaching its relaxed state, therefore high pressure is maintained
    • important for exchange organs and keeping pressure high before entering the capillaries
    • arteries also contain fibrous tissue that is not found in the much narrower arterioles
  16. unidirectional flow
    • requires two valves that prevent backflow and second vessel that refills that chamber in the heart
    • contraction of chamber increases pressure in chamber, allowing blood to flow to low pressure upper vessel while closing valve to lower vessel
    • expansion of chamber causes blood to flow from high pressure of lower vessel into the chamber, while closing the valve to upper vessel which has higher pressure
    • in model of one chamber and one vessel with no valves, blood goes back and forth in bidirectional flow
  17. pressure during cardiac cycle
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  18. electrocardiogram - PQRST
    • measures changes in voltage within the heart
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  19. P wave
    • depolarization of SA node
    • gap at atrial systole and raid depolarization of AV bundle
  20. QRS wave
    • Q depolarization AP propagating through Purkinje fibers
    • repolarization of SA node
    • RS ventricles depolarized and contracts
    • corresponds to ending of atrial systole and beginning of ventricular systole
  21. T wave
    • repolarization of ventricles
    • gap during diastole of both atria and ventricles
  22. autorhythmic cells
    • arranged in two nodes that are connected by fibers that allow for rapid transmission of AP
    • nodes are the SA or sinoatrial node AV or atrioventrical node
    • contain gap junctions
  23. contractile cells
  24. SA node
  25. AV node
    • concentration of autorhythmic cells at atrial-ventricular border
    • need to be activated by AP from the SA node via the internode fibers (AV bundle)
    • fire at lower rate than under normal physiological conditions due to action by SA node
  26. pacemaker potential
  27. Purkinje fibers
    • at apex end of heart
    • bottom-up configuration allows for blood to be squeezed through the semilunar valves
  28. law of continuity
    • volume in / time = volume out /time
    • flow speed is denoted with u
    • increase in area leads to proportionate decrease in flow rate or speed
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  29. flow velocity in cardiovascular system
    • physiologically, differences in blood flow velocity is managed by the relative cross-sectional area of the different blood vessels
    • left heart has a smaller area (4cm^2) than the right heart (6cm^2), so flow velocity is faster in the left heart
  30. pressure during transport
    • the smaller the blood vessel, the more resistance from the vessel walls
    • in the systemic arteries, systolic pressure is maximum pressure and diastolic pressure is minimum pressure
    • diastolic pressure in the arteries is much higher than in the ventricles
    • right heart is smaller and generates less pressure than left heart
    • veins have low pressure but high velocity
    • drop is pressure in capillaries caused by high resistance due to viscosity and small vessel radius
  31. increasing dissolved O2 in air/solution interface
    • increase air pressure
    • increase proportion of O2 in air
  32. ideal gas law
    • PV= nRT
    • decrease volume causes proportional increase in pressure
    • if n (number of moles) constant, then P1V1 = P2V2 or Boyle's Law
  33. Dalton's Law
    • PO2 = Ptotal x %O2 in air
    • total pressure equals sum of partial pressures
  34. partial pressures of O2 and CO2
    dissolved gases travel from high partial pressure to low partial pressurepartial pressures differences is how oxygen enters blood and CO2 leaves blood during gas exchange

    • % in air  O2 = 21   CO2 0.033
    • P in air (mmHg)   O2 = 155   CO2 = 0.24
  35. solubility of O2
    • solubility of O2 in water is 0.8 ml/L
    • solubility of O2 in plasma is 3.0 ml/L
    • body needs 250 ml/min of O2 but plasma can only deliver at 15 ml/L (6% of demand)
    • red blood cells required to deliver O2 to cells
  36. red blood cell
    • each RBC contain millions of protein complexes called hemoglobin
    • each hemoglobin have 4 heme groups that contain iron which can bind O2
    • RBC have no nuclei
  37. oxygen uptake process
    • 1) O2 diffuses into plasma
    • 2) increase of PO2 casuses Hb to bind O2
    • 3) Hb binding maintains O2 gradient
    • 4) PO2 in blood achieve the PO2 in the alveoli (also applies to CO2)
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  38. oxygen-hemoglobin dissociation
    • at high O2 saturation (~75%), a large increase in PO2 is needed to saturate blood
    • at low O2 saturation, a small decrease in PO2 is needed to release O2
    • useful for suppling O2 to cells that have low PO2
    • lower pH, higher PCO2, and higher temperature (caused by increased activity) act to lower the dissociation curve
  39. CO2 transport
    • only 7% dissolved in plasma
    • 23% binds to Hb
    • 70% transported as bicarbonate
    • within the RBC, follow reaction occurs
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    • bicarbonate is removed from RBC via an antiporter with Cl-
    • blood pH drops due to H+
  40. PO2 and PCO2 during circulation
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  41. anatomy of thoracic cavity
    • thoracic cavity
    • trachea
    • bronchiole
    • alveoli (singular alveolus)
    • diaphragm
  42. inhalation
    • contraction of diaphragm
    • cavity expansion and elevation aided by external intercostals and scalenes
    • increased volume in lungs 
    • air drivies toward relative low pressure inside lungs
  43. exhalation
    • relaxation of diaphragm
    • cavity decrease aided by intercostals and abdominal muscle
    • decreased volume in lungs
    • air is driven toward relative low pressure of outside environment
  44. pleural cavity
    • fluid filled closed sac betwen lung tissue and rib cage
    • lubricates and allows sliding of lung tissue with respect to the ribs
    • functions to keep alveoli inflated by maintaining a lower pressure than the pressure inside of the alveoli
    • collapsed lung results from rupture of pleural cavity, so pleural can no longer pull on alveoli and keep them inflated with some volume of air
  45. changes in lung volume, pressure, and volume during breathing
    • pressure equilibriates in the lungs after inspiration since it is an open system; in other words, air stops entering lungs when we stop inhaling since there is no longer a pressure difference (air has caught up with change in lung volume)
    • pleural cavity does not equilibriate since it is a closed system
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  46. respiratory cycle
    • dead space of 150 ml remains fixed with varying respiration rate
    • tidal volume during shallow breathing is 500 ml
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  47. pulmonary ventilation - equation
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  48. alveolar ventilation
    • measure of how much air reaches the avleoi
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  49. effects of varying alveolar ventiliation
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  50. small intestine
    • two sphincters at beginning and at end
    • only need to know duodenum, the first section that participates in nutrient absorbtion
    • from beginning to end, a continuum of high to low absorption exists (similar to nephrons)
  51. duodenum anatomy
    • composed of gastruc mucosa, a collection of epethelium and connective tissue surrounded by smooth muscles
    • epithelium has villi and crypts
    • capillaries and lacteals imbedded underneath villi
    • each villus composed of microvillus
    • villi also have goblet cells and endocrine cells
  52. neutralizing stomach acid
    • 1) low pH triggers release of secretin by endocrine cells
    • 2) secretin inhibits acid secretion in stomach
    • 3) secretin stimulates bicarbonate secretion in the pancrease
    • 4) bicarbonate neutralizes HCL with the follow equation -
    • H+ + Cl- + HCO3- + Na+ = H2CO3 +NaCl
  53. pepsin down regulation
    pepsin from stomach is neutralized by high pH triggered by secretin
  54. cholecystokinin - CCK
    • fats in duodenum trigger release of CCK
    • CCK downregulates activity of smooth muscle surrounding duedenum via ligand gated channels, leading to reduced motility
    • chyme slows down and allows time for greater breakdown
    • CCK also upregulates smooth muschle around gall bladder, triggering bile salt release via common bile duct (liver produces bile, gall bladder only stores it)
    • CCK also stimulates pancreas to release enzymes (including trypsin, colipase, amylas), ions, and water
  55. carbohydrate digestion
    • glucose polymers like starch and glycogen are broken down by amylase into disaccharides
    • common disaccharides are maltose, sucrose, and lactose
    • these are broken down by maltase, sucrase, and lactase, respectively, into monosaccharides; these enzymes are located at the brush border
    • common monosaccharides are glucose, fructose, and galactose
  56. carbohydrate absorption
    • monosaccharides are absorbed via transporters
    • three players include SGLT symporter, Na+K+-ATPase, and GLUT2 transporter using facilitated diffusion
  57. protein digestion
    • proteins contain amino terminal and carboxy terminal
    • endopeptidases like pepsin and trypsin break internal peptide bonds into small peptides and tripeptides
    • exopeptidases like carboxypeptidase break down terminal peptide bonds (at amino and carboxy terminals)
    • end up with amino acid or dipeptide
  58. protein absorption
    • amino acids are cotransported with Na+ (via symporter) and exit the gastric mucosa via facilitated diffusion
    • di- and tri-peptides are cotransported with H+ then use facilitated diffusion
    • small peptides are transported via transcytosis (packaged into a vessicle and moved across the cell, so never really encounters the cell's internal environment)
  59. fat digestion
    • fat droplets are packaged with bile salts into smaller droplets called micelles, creating larger surface area for interaction with enzymes
    • micelles contain triglycerides and cholesterol
    • pancreas secretes lipase and colipase enzymes that break down triglycerides into monoglycerides and free fatty acids
  60. fat absorption
    • monoglycerides and free fatty acids diffuse freely into cell since they are lipophilic, they then enter the sarcoplastic reticulum
    • cholesterol enters via a transporter
    • all three fuse with the golgi apparatus and then released into interstital fluid where they are picked up by lacteals and enter the lymph system
  61. large intestine anatomy
    • two sphincters at beginning and at end
    • rectum and anus at terminal end
    • major functions include water absorption, housing of bacteria that help with digestion of carbs and proteins and provide vitamins, and storage and condensing of feces
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E109 Midterm 2
2012-08-29 09:25:51
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midterm 2
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